A modified asphalt Contactor reactor for blending and reacting asphalt cement and modifiers is described; for example, a vertically oriented vessel having an outer shell having an internal surface and an external surface, a lower end and a flat flanged top; an internal circulation tube having a base, a top and an outside surface, wherein the outside surface of the internal circulation tube and the internal surface of the outer shell forms an annulus; a heating jacket having heating oil inlet and a heating oil outlet coupled to the external surface of the outer shell for circulation of heating oil; and a hydraulic head assembly having an impeller coupled to the lower end the vertically oriented vessel wherein the impeller is located near the base of the internal circulation tube, wherein the impeller and the annulus are of sufficient size to facilitate the flow of high viscosity fluids.